Electrical Question 68 Coupe

[Kurt B.]

I hate electrical!!
The bulb that lights up the Heater and A/C control on the shifter console does not light, however, when inserting a 12 volt test light into the socket, the test light lights up perfectly. I assumed, incorrectly, it was a bad bulb. Have replaced with several new bulbs but bulbs will not light.
With a bulb in place, if I ground my test light and then touch the probe of the test light to the side of the metal base on the bulb, the bulb glows faintly.
What is the problem? Poor ground? How is the console shifter plate grounded?
My restoration project is going backward and this problem has me taking my interior apart rather than finishing it.
Getting very frustrated.
Thanks for any help.
Kurt # 26406

[mike cobine]

Re: Electrical Question 68 Coupe

Bad ground. It could be the socket isn't grounding to the console panel as I am assuming your gauges are working. If they were not, then the whole panel isn't grounding.

If you are frustated, think of those poor guys when 1953 Corvette 001 and 002 rolled off the end of the line. Don't you know that was a bad day.

[Dick W.]

Re: Electrical Question 68 Coupe

It is a ground problem. At the present time my wiring schemetics are not available to me. Maybe someone else can tell you where the ground is.

[Henry J.]

Re: Electrical Question 68 Coupe

Kurt:

My 68 has a ground terminal on the shifter console plate. It is shown as item 5 in the AIM on UPC 12 Sheet B2. The ground wire is shown on UPC 12 Sheet B7 with the note "To Console Ground" and again in the top right-hand corner of the wiring diagram, UPC 12 Sheet D3.

If your dash wiring harness has been butchered, the ground wire may be missing.

I hope this helps.

Henry
Newmarket, Ontario

[Kurt B.]

Re: Electrical Question 68 Coupe

The socket has a gray wire that goes to the center of the socket and touches the center contact of the bulb and a black wire that comes from the side of the socket and makes contact with the metal base (side)of the bulb. Apparently the black ground wire isn't providing a good ground, because when you both suggested it was a bad ground I ran a separate ground wire to the frame and touched the side of the new bulb (old one was shot) it lit up perfect. When I did the same thing with my test light earlier it only glowed very dimly whihc is why I did not think it was ground. Did I mention I hate electrical.
I assume there is no problem with me running a separate ground wire for this fixture? Will I do any damage by doing so?
All other lights, gauges, fans, etc. work perfect, just this one lamp doesn't.
Thanks for the help. I am in over my head when it involves wires: mental block I guess.
Kurt

[Kurt B.]

Re: Electrical Question 68 Coupe

Henry,
Thanks for the tip. I looked in the AIM and found what you are referring to. My clip is gone so that may be part of the problem. I will remedy that. Thanks for pointing me to the correct reference.
Kurt

[Terry F.]

Re: Electrical Question 68 Coupe

What Henry said, Terry

[Jack H.]

Re: Electrical Question 68 Coupe

OK, now you've put science to work (read the AIM, find the ground and verify it), good! One last comment before you go to button things up...

Check the bulb you're using against the owner's manual! The lamp used to illuminate the center console climate control module is a different part than that used in other dash illumination sockets...

Specifically, a standard dash lamp will fit/work but it'll poorly illuminate the climate control module. The lamp that was originally used had a different style globe (long and skinny to 'reach' up inside the module) picked for that specific application.

[Kurt B.]

Re: Electrical Question 68 Coupe

Jack,
You are (of course) correct. The one that burned out was long and skinny. I purchased an entire dash bulb set from Dr. Rebuild and just happened to have the correct bulb in stock for once.
Still can't figure out howto replace the lens between the thumb wheels.
Kurt

[Mike Baker]

Re: Electrical Question 68 Coupe

Kurt,

I'm not sure how much different the AC makes that assembly. I do have some pictures from when I took mine apart (without AC). I would be happy to forward them if you will post an email address.

There are a couple tabs that are crimped over to hold the face to the housing the lamp snaps into. The hairiest part of cleaning that thing up was opening then re-crimping those tabs without breaking them off.

[Klaus Friedrich #33362]

Re: Electrical Question 68 Coupe

Hi Kurt,

it's hard piece of work to change the lens.
I think the engineers never ever thought of changing it.

You'll need a whole day when you'll do that.
First problem is to remove the wire for the heater control.
The lens is held by noses from the casting (zinc) that need to be bend open and must be closed again. So be careful.

Good luck and much fun ...

Klaus Friedrich #33362
Germany

[Kurt B.]

Thanks to all, for the replies. *NM*